"Etching" onto a cube
Steps for creating the below image:

take the default cube
add a subdivision surface modifier set to simple, with 7 levels
add a displacement modifier and choose your image texture, adjust strength so it doesnt displace it too much.


The actual engraving gets done with the displace, where you select Image Texture, and then use whatever image you want. However, displacement acts only on the existing geometry, so you need to make sure your mesh has enough detail to apply the texture to. To solve this, I have a subdivision surface set to simple (so it doesnt change the geometry) added before the displace:

I hope this is what you're looking for.